Ok so recently did the opti on my car and while I was in there I ripped out the air pump and all the other crap . I didn't cut off the things front he exhaust manifolds yet just have it capped off with a rubber cap . I wanna cut it off and plug it properly I just don't know why size thread I need Ina bolt to plug it . I saw someone do it on an impala and they used a cap but I pretty sure the camaro and firebird exhaust manifolds are different . Any help highly appreciated . Thanks guys

 

Depends on your car (you don't list what you have). M18 plug for OBDII cars, M22 for OBDI. Just confirm on that via search - my memory isn't what it used to be.

 

My 95 TA was an 18m x 1.5 the same threads as on a o2 sensor I had laying around so I searched and came up with buying 2 oil drain plugs

 

Oh sorry guys I was searching real late last night I was real tired lol. I have a 1994 lt1 z28 my bad guys

 

What ram air said